The invention relates to a transport system for transporting preforms in a device for the blow-molding production of finished containers, wherein the transport system comprises a transport chain, the chain elements of which comprise a support element and a transport element. The invention also relates to a device for the blow-molding production of finished containers from preforms, as well as a use of the transport system, and a method for exchanging at least one support element of the transport system.
In order to package liquid foods and beverages, normally containers such as, e.g., bottles made of glass or plastic are used, which are created on various devices in a production process and subsequently filled on a further device. Examples of this would be the production of containers made of plastic in a blowing device. When forming containers through the effect of blowing pressure, preforms of a thermoplastic material, for example preforms of PET (polyethylene terephthalate), are supplied to different processing stations within a blow molding machine. Typically, such a blow molding machine has a heating mechanism as well as a blowing mechanism, in the region of which the previously temperature-controlled preform is expanded into a container through biaxial orientation. The expansion takes place with the assistance of compressed air, which is introduced into the preform to be expanded, and optionally an additional extension. The process-engineering sequence with such an expansion of the preform is explained, for example, in DE-OS 43 40 291. The introduction of the pressurized gas also comprises the introduction of pressurized gas into the developing container bubble as well as the introduction of pressurized gas into the preform at the start of the blowing process. The basic structure of a blowing station for forming containers is described in DE-OS 42 12 583. Possibilities for the temperature control of the preforms are explained in DE-OS 23 52 926.
During the production and filling processes, it is necessary to transport the containers and transfer them from one station to another between the individual process steps. The preforms as well as the blow-molded containers can be transported within the device for blow molding with the assistance of different handling devices. Particularly the use of transport mandrels, onto which the preforms are placed, has been tried and tested.
An exemplary device with transport mandrels for transporting the preforms and containers is known from EP 2 753 465 A1. The blowing mechanism comprises multiple blowing stations, which are arranged on a rotating blowing wheel, for forming the preforms into the finished containers, as well as retaining devices for retaining and transporting the preforms. The retaining devices shown in EP 2 753 465 A1 have multiple, namely at least two, positionable clamping elements in the region of their head, said head being insertable into an opening section of the preform, said clamping elements being rounded at least in regions and being arranged spaced relatively apart from one another along an outer circumference, thus being circumferentially spaced apart from one another. At least one of the clamping elements is positioned in a recess arranged laterally on the head with respect to a longitudinal axis of the retaining device, wherein the recess has upper and lower sliding surfaces, extending diagonally with respect to the longitudinal axis, for impacting the clamping element and wherein the head has a head lower part provided with the lower sliding surface and a head upper part provided with the upper sliding surface. The preform in this case is substantially formed with a cylindrical inner surface in the region of its opening section. Suitable further clamping elements for transporting preforms are described, e.g., in DE 10 2005 011 805 A1 and DE 10 2008 023 701 A1.
The transport mandrels used for transporting the preforms must be replaced regularly, for example to reset the device for the blow-molding production of finished containers for a different type of preform or for replacing worn or soiled parts. The exchanging of the transport mandrels is relatively complex and must be carried out manually. In order to reduce the work effort required for exchanging the transport mandrels, a stable transport system with automatically exchangeable transport mandrels for preforms would be desirable, which enables a quick change of the transport mandrels despite stable retention of the preforms.
Thus, the object of the present invention is to design a device of the aforementioned type such that reliable transport of the preforms is supported at a high transport rate and additionally quick exchanging of the transport mandrels is ensured.